[MIPS] Rename MIPS sys_pipe syscall entry point to something MIPS-specific.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/scall32-o32.S

@@ -354,7 +354,7 @@ einval:	li	v0, -EINVAL
 	sys	sys_mkdir		2
 	sys	sys_rmdir		1	/* 4040 */
 	sys	sys_dup			1
-	sys	sys_pipe		0
+	sys	sysm_pipe		0
 	sys	sys_times		1
 	sys	sys_ni_syscall		0
 	sys	sys_brk			1	/* 4045 */

arch/mips/kernel/scall64-64.S

@@ -219,7 +219,7 @@ sys_call_table:
 	PTR	sys_readv
 	PTR	sys_writev
 	PTR	sys_access			/* 5020 */
-	PTR	sys_pipe
+	PTR	sysm_pipe
 	PTR	sys_select
 	PTR	sys_sched_yield
 	PTR	sys_mremap

arch/mips/kernel/scall64-n32.S

@@ -141,7 +141,7 @@ EXPORT(sysn32_call_table)
 	PTR	compat_sys_readv
 	PTR	compat_sys_writev
 	PTR	sys_access			/* 6020 */
-	PTR	sys_pipe
+	PTR	sysm_pipe
 	PTR	compat_sys_select
 	PTR	sys_sched_yield
 	PTR	sys_mremap

arch/mips/kernel/scall64-o32.S

@@ -247,7 +247,7 @@ sys_call_table:
 	PTR	sys_mkdir
 	PTR	sys_rmdir			/* 4040 */
 	PTR	sys_dup
-	PTR	sys_pipe
+	PTR	sysm_pipe
 	PTR	compat_sys_times
 	PTR	sys_ni_syscall
 	PTR	sys_brk				/* 4045 */

arch/mips/kernel/syscall.c

@@ -40,7 +40,14 @@
 #include <asm/sysmips.h>
 #include <asm/uaccess.h>
 
-asmlinkage int sys_pipe(nabi_no_regargs volatile struct pt_regs regs)
+/*
+ * For historic reasons the pipe(2) syscall on MIPS has an unusual calling
+ * convention.  It returns results in registers $v0 / $v1 which means there
+ * is no need for it to do verify the validity of a userspace pointer
+ * argument.  Historically that used to be expensive in Linux.  These days
+ * the performance advantage is negligible.
+ */
+asmlinkage int sysm_pipe(nabi_no_regargs volatile struct pt_regs regs)
 {
 	int fd[2];
 	int error, res;